Oil contained in the strata of subterranean formations is necessary for maintaining present domestic and industrial activities and for the advancement of science in industry generally.
An ever increasing need exists for greater supplies of oil derived from subterranean formations. Locating such oil bearing formations which are accessible and which produce a fluid in sufficient quantities to be economically operable to meet the needs for such oil is among the more important needs of the world. Also, continued production of oil from such formations for a period of time sufficient to remove a substantial portion of the oil therefrom at a minimum of operating costs and deterioration of equipment is of great importance.
Conditions which adversely affect the production of oil from a well include (1) plugging or blocking of the passageways in the formations leading to the well due to both natural and structural conditions and the deposition of plugging materials brought out during production (e.g. water blocks, emulsions of water and oil, deposition of high boiling constituents of oil and of sand and detritus generally from unconsolidated formations; (2) insufficient pressure to force the fluid through the formation to the well; and (3) corrosion of the well tubing and operating equipment in the well. Treatment of a well as by introducing an oil field chemical into the formation traversed thereby is among the more effective measures employed to increase the rate of production, prolong the producing life, and lessen the deterioration of well equipment.
In accordance with this invention, these objectives are achieved by placing an oil field chemical in microcapsules of the condensation product of hydroxyacetic acid monomer or a co-condensation product of hydroxyacetic acid and compounds containing other hydroxy-, carboxylic acid-, or hydroxycarboxylic acid moieties and thereafter introducing such microcapsules into an oil well bore and/or subterranean oil formation where the oil field chemicals are released as the microcapsules degrade in the presence of moisture to form oil and water soluble products.